So that textiles fulfill their purpose of use and have the desired properties with respect to feel, appearance and use behavior, they are specially processed. Apart from obtaining the fiber, yarn and twist production and fabric production, there are further methods, which influence the textile properties.
Depending on the purpose of use, for example, a greater stability, a higher temperature resistance or more volume are desired in the thread-like material.
These properties are achieved by so-called finishing methods, which can be carried out in all the process stages. There are finishing methods for fibers, yarns/twists and fabrics. Some finishing methods can be integrated in the production or further processing process, but others are in turn discontinuous.
Many of these finishing methods require a subsequent thermal setting, which is generally carried out in a steam atmosphere or under dry heat in order to permanently stabilize the desired properties. The setting process is generally called thermosetting in the textile industry but the synonym heat-set process is used in the area of carpet yarn production.
In the area of carpet yarn production, for example, there are so-called straight set yarns and frieze yarns.
In the case of straight set yarn, the straight linear structure of the single yarns or the cabled yarns or twists is thermoset, which leads to straight pile loops arranged next to one another in cut-pile carpets.
A three-dimensional formation is imposed on the yarn in a separate process for frieze yarns between the cabling process and the heat-set process. In this case, the yarn is three-dimensionally formed by bending/compression and this state is thermoset. The yarns are formed like a walking stick in the finished carpeting in the case of cut-pile carpets. The carpets exhibit a lively surface structure, which is non-sensitive to footprints. More than half the cabled yarns or twists processed in cut-pile tufted carpets worldwide are given a so-called frieze appearance or textured appearance in a thermo-mechanical process.
After forming, the cabled yarns or twists are subjected to a subsequent thermosetting process. Owing to the successive heating and cooling, the yarn relaxes and, depending on the type of material, may shrink and bulk. Furthermore, the yarn twist is permanently stabilized or set thereby, which, in later use of the yarns, leads to substantially improved wear-resistance and durability of the carpets or carpeting produced therefrom.
In practice these methods are carried out by single units that are independent of one another.
A method and a device for thermosetting carpet yarn using different yarn depositing mechanisms is disclosed by U.S. Pat. No. 5,467,513. Furthermore, the device and the method are to be able to modify existing thermosetting machines in such a way that the most varied yarns from straight set yarn to highly crimped yarn can be produced.
This is to be achieved by a yarn depositing system for depositing the yarn in predetermined laying patterns on a conveyor belt. The yarn is then transported on the conveyor belt through the thermosetting mechanism. The yarn depositing is controlled by different laying patterns in such a way that yarns textured to different extents can be produced.
A controllable, oscillating yarn delivery tube for depositing the yarn in different laying patterns on the conveyor belt is configured in such a way that a change can be made between the straight set yarn production and the texturing of the yarn. The drive motor of the oscillating yarn delivery tube is correspondingly controlled for this purpose. Moreover, an adjustable baffle plate is additionally arranged above the conveyor belt so the yarn, which exits from the yarn delivery tube, firstly impacts on the baffle plate and is then deposited on the conveyor belt. In order to assist the drawn transportation of the yarn to the exit of the yarn delivery tube, compressed air is fed to the yarn delivery tube through an injection nozzle.
The drawback in the method and the device is that the texturing by means of predetermined laying patterns is firstly produced during the depositing on the conveyor belt. However, it has been found in practice that a random production of the textured effect brings about a livelier surface structure of the yarns in the finished carpet. In addition, not all the yarn counts can be equally formed with the loop depositor, and above all narrow limits are imposed in the case of coarser yarn counts with this device. Because of this knowledge, both the method and the device according to US Pat. No. 5,467,513 have not been accepted in practice.
A thread finishing system is described in German Patent Publication DE 198 25 905 A1. Depending on whether a crimped or uncrimped thread is to be produced, the latter runs through a corresponding alternatively used unit and is deposited on a conveyor belt. On the conveyor belt, the thread is finally fed to an air-conditioning chamber for thermosetting. As different units are used for producing crimped or uncrimped threads, an adapter arranged downstream of the delivery roller pair is disclosed, which reduces the assembly outlay for converting the finishing system.
According to German Patent Publication DE 198 25 905 A1, in order to be able to produce crimped threads (in the textile area, the terms compressed, formed threads or threads with a frieze effect are used as synonyms), a so-called compression chamber is used. The compression chamber, apart from a channel inlet and a channel outlet, has a through-channel A so-called retaining flap is arranged on the channel outlet, with a joint on the channel wall, said retaining flap exerting a retaining force counter to the transporting direction of the threads to be compressed. The threads to be compressed reach the through-channel via the channel inlet and are braked here on the walls of the through-channel and by the retaining flap until the yarn plug is so large that the retaining force of the retaining flap is overcome and the threads come to rest on the conveyor belt via a sliding face arranged downstream of the channel outlet. Following this, the threads are fed on the conveyor belt to a separate thermosetting mechanism.
If, on the other hand, uncrimped threads or straight set yarns or twists are to be produced, a so-called loop depositor is necessary for this. The loop depositor contains a hollow shaft, into which a depositing tube projects. Together with the hollow shaft, the depositing tube can be driven to traverse. The threads, which are fed by the delivery roller pair, arrive through an inlet tube in the through-channel and finally in the channel of the traversing depositing tube, so the threads are deposited in the form of thread loops on a conveyor belt in order thereafter to run through a separate thermosetting mechanism. Ignoring the bending radii, uncrimped or straight set threads are referred to.
However, it is a drawback in the devices that to achieve the frieze or straight set effect, individual units are used, so to change from one effect to the other, it is necessary to convert mechanical components and to rethread the thread-like material, which leads to downtimes of the textile machine and impairs productivity.